Filler Surface Research Articles

Analysis of Surface Characteristics of Printing Paper Using Contact Profilometry

The surface roughness and frictional properties of printing paper can significantly impact ink transfer and printability during the printing process. Therefore, the aim of this study was to investigate the surface characteristics of paper in relation to its physical and chemical properties. Surface characteristics were analyzed using profilometry, and the physical and chemical properties of the paper were evaluated based on fiber and filler properties. The results revealed a significant correlation between filler behavior and surface properties. Furthermore, the mean absolute deviation (MAD) as a parameter representing the absolute deviation from the mean value, indicated that the variability depending on the measurement conditions was relatively small in the evaluation of the surface characteristics. Therefore, it is expected that the application range will be wide in the future.

Polymer‐based nanocomposites in semiconductor packaging

AbstractSemiconductor packaging materials play a critical role in the development of semiconductor devices. They not only provide reliable protection and support, but also contribute to the electrical connection between the chip and the external circuit. Among many choices of packaging materials, polymer‐based nanocomposites have become the mainstream candidate due to their low cost, easy processability, and tunable properties. Materials with low dielectric constant and dielectric loss, high glass transition temperature, fast thermal conductivity, suitable coefficient of thermal expansion, low viscosity, and good processability are commonly required in semiconductor packaging, yet most polymers do not meet these criteria. Therefore, modulation of the polymer matrix, introduction of suitable fillers, and modification of the filler surface are often effective approaches to enhance the performance of the composites. Here, the authors first review current research progresses of polymer‐based nanocomposites for five different types of packaging applications, namely moulding compounds, thermal interface materials, underfills, die attach materials, and substrates. The authors then present prospects of developing next‐generation polymer‐based nanocomposites for advanced semiconductor packaging and propose some suggestions to solve the existing challenges.

Hydrogel microbial reactor based on microbially induced calcium precipitation for the removal of calcium, cadmium and nitrate from groundwater

In this study, hydrogel biocarriers filled with chia seeds gum biochar encapsulated with Pseudomonas sp. LYF26 were prepared using polyvinyl alcohol and sodium alginate. Simultaneous removal of NO3−, Ca2+ and Cd2+ from low carbon wastewater was achieved by microbially induced carbonate precipitation and denitrification. In order to investigate the performance of the bioreactor, different conditions of hydraulic retention time, pH, and concentration of Cd2+ were studied, and the optimal operating conditions of the bioreactor were finally determined as HRT of 8 h, pH of 6.5 and initial Cd2+ concentration of 3 mg L−1. The results showed that the optimum removal of NO3−-N, Ca2+ and Cd2+ by the reactor was 100%, 54.02% and 100%, respectively. Three-dimensional excitation-emission matrix (3D-EEM) showed that the microorganisms produced extracellular polymers during the operation of the bioreactor, which promoted the removal of Cd2+. Fourier transform infrared spectroscopy (FTIR) detected the presence of -OH, CO, C-O-C and C-O-H, indicating the production of CaCO3 and extracellular polymers. Scanning electron microscope (SEM) observed that the filler surface had a rough and porous character with a large amount of biodeposits attached to its surface. X-ray diffraction (XRD) indicated that the sediments contained CaCO3, CdCO3 and Ca5(PO4)3OH. High-throughput sequencing showed that Pseudomonas was the dominant bacterium.

A brief review on preparation and application of MWCNT-based polymer nanocomposites

Technological advancementalways seeks new materials with improved functional properties, particularly for smart applications. In this regard, nanotechnology is offering today wide range of novel material designs fabricated by compounding nanofillers into the polymer matrix. Different allotropic forms of carbon can reinforce the properties of polymers for various applications. Reinforcement depends on the dimension, shape, size and compatibility of the nanofiller with the polymer matrix. Chemical modification of filler surfaces and the matrix can selectively localize the filler in the hybrid composites in the desired phase or at the interface by melt mixing or solution casting method, during compounding procedure. In this regard, the conducting nature of the additioin of multiwalled carbon nanotubes (MWCNTs) into a polymer matrix fosters the conductivity into the materials. Such nanocomposites can be used for numerous applications such as conducting materials, super-capacitors, light emitting devices, medical purposes etc,. This review paper focuses on different methods of preparation of MWCNT/polymer nanocomposites, their surface properties, and microbial properties etc,.

Uncoordinated chemistry enables highly conductive and stable electrolyte/filler interfaces for solid-state lithium–sulfur batteries

Composite-polymer-electrolytes (CPEs) embedded with advanced filler materials offer great promise for fast and preferential Li+ conduction. The filler surface chemistry determines the interaction with electrolyte molecules and thus critically regulates the Li+ behaviors at the interfaces. Herein, we probe into the role of electrolyte/filler interfaces (EFI) in CPEs and promote Li+ conduction by introducing an unsaturated coordination Prussian blue analog (UCPBA) filler. Combining scanning transmission X-ray microscope stack imaging studies and first-principle calculations, fast Li+ conduction is revealed only achievable at a chemically stable EFI, which can be established by the unsaturated Co-O coordination in UCPBA to circumvent the side reactions. Moreover, the as-exposed Lewis-acid metal centers in UCPBA efficiently attract the Lewis-base anions of Li salts, which facilitates the Li+ disassociation and enhances its transference number (tLi+). Attributed to these superiorities, the obtained CPEs realize high room-temperature ionic conductivity up to 0.36 mS cm-1 and tLi+ of 0.6, enabling an excellent cyclability of lithium metal electrodes over 4,000 h as well as remarkable capacity retention of 97.6% over 180 cycles at 0.5 C for solid-state lithium-sulfur batteries. This work highlights the crucial role of EFI chemistry in developing highly conductive CPEs and high-performance solid-state batteries.

Molecular simulation of crystal nucleation and growth of structurally restricted polymer nanocomposites

This study reveals important features of crystal nucleation and growth in coarse-grained structurally restricted polymer systems (i.e., one end of the chain is grafted on the surface of one-dimensional filler) based on the Monte Carlo simulation on cubic lattice. The structurally restricted polymer system includes two kinds of polymers: terminally grafted and free chains. The existence of more grafted chains increases the crystal nuclei number in the structurally restricted polymer systems, which shortens the nucleation induction time and accelerates crystallization. Intramolecular nucleation occurs when the chain structure is limited. Then, with the increase of restricted chains, the nucleation mechanism changes to intermolecular nucleation. When the interface interaction is introduced into the system, the change of crystallization rate is the result of the competition between conformation entropy and chain mobility. The chain elongation increases with the enhancement of interface interaction, which leads to the increase of the loss of conformational entropy and is conducive to the formation of crystal nucleus. However, the chain mobility slows down with the enhancement of interface interaction, which will hinder the formation of crystal nucleus. By tailoring the interface interaction, the crystal morphologies of polymer nanocomposites can be adjusted to form the unique nanohybrid shish-kebab structures, that is, the filler is used as shish, the crystal regions generated by free chains are attached to the outside of crystal regions generated by restricted chains to form kebabs. Furthermore, the length of grafted chains has different effect on the crystallization depending on the concentration of grafted chains.

Quantitative measurements of changes in agglomerate size with oscillatory shear strain in polymer nanocomposites using online dielectric analysis

Shear strains during processing affect the agglomerate size of nanoparticles in nanocomposites and their final behavior in various applications. In this study, dielectric characterization technique as a novel and well-effective method is applied for quantitative measurement of average agglomerate size in polymer nanocomposites under shear strain sweep, combining with an existing analytical model. Examining how changes in filler content, surface energy and polarity of particles and the matrix control the strain-dependency of agglomerates size, two different nanoparticles, namely, titanium dioxide (TiO2) and carbon black (CB), with same average diameters and volumes were added to polystyrene (PS). It was found that larger agglomerates were present in the PS/CB nanocomposite prior to shearing and the CB agglomerates were less prone to deagglomeration under shear strain. This behavior was attributed to higher polarity of CB nanoparticles, leading to higher tendency for agglomeration and higher resistance to shear, in respect to TiO2 nanoparticles.

INVESTIGATION OF THE WETTING EFFECT OF SURFACTANTS OF VARIOUS NATURE IN THE BITUMEN COMPOSITION

Asphalt concrete coverings are short-lived and are destroyed under the influence of external factors. The insufficient degree of adhesion at the interface between the bituminous binder and the hard surface of the mineral material causes a low hydrophobicity of asphalt concrete coatings, which is the main cause of damage and premature wear of the roadway. Optimization of the bitumen composition by introducing a variety of modifying agents can intensify the processes of wetting the hard surface with bitumen and increase the hydrophobicity of the surface films formed by it. The purpose is to establish the influence of various modifiers on the processes of wetting the surface of crushed stone with a bituminous composition, as well as to study the regularities of the influence of modifiers on the hydrophobicity of bituminous films. The methodology of this work included experimental determination of the wetting contact angle θ of a solid surface by the lying drop method at T=298 K. Results. Increasing the AC-2K content in bitumen from 0 to 1% reduced the contact wetting angle by 11.31° (relative to the base version without the modifier) to 114.35°. The AC-2 modifier contributes less to improving the wettability of the surface of the basic crushed stone with bitumen; with Cm=1%, the contact wetting angle is reduced to 118.68°. When modifying bitumen, PPS recorded a significantly smaller decrease in wetting contact angle at a higher concentration (Cm=2%) – by 2.4° (from 125.66° to 123.26°). The amino derivative AC-2K (Cm=1%) has the greatest water-repellent effect among the studied modifiers, increasing the wetting edge angle to 99.07°. Conclusion. The water-repellent properties of bituminous compositions are enhanced (Δθ=4.02°) at a narrow range of concentrations of the modifier AC-2K (with Сm=1%). The ultrasonic cavitation-derived AC-2K can be recommended for use in asphalt concrete coatings as an adhesive additive that provides a good wetting effect of bitumen in relation to the surface of the mineral filler while also increasing the hydrophobicity of bitumen films.

Preparation of Wood Filler for Arbolite

The effect of treating the wood filler of freshly cut wood species with the additive of silica sol obtained by the polycondensation method on the arbolite properties is studied. It was found by X-ray fluorescence spectroscopy that silica sol particles with the sizes of 20 to 80 nm are adsorbed on the surface of the wood filler, obstructing open pores and spaces between the wood vasculars. The most effective is the additive of silica sol with its content from 10 to 20%. It is shown by the a multilayer map of energy-dispersive X-ray spectroscopy of a wood particle treated with silica sol that calcium cations accumulate on the wood filler in the arbolite mix, thus affecting the hydration of the cementing material and the arbolite strength. After 3 and 28 days of hardening, the strength of the arbolite with the birch chips increases by 2.5-2.7 and 2.7-3.1 times, respectively; with the aspen chips its strength becomes 3.1-4.2 times higher; and the arbolite strength rises 3.1-4.2 times with birch and pine chips (1:1). The method for treating the wood filler with silica sol patented by the authors makes it possible to simplify the technology of its preparation, to reduce the exposure time of wood filler before mixing with a cementing material and to produce arbolite from freshly cut birch wood with the strength after 3 and 28 days of hardening being 2.5-2.7 and 2.7-3.1 times higher than that of the control composition.

Chemical and Structural Assessment of New Dental Composites with Graphene Exposed to Staining Agents.

Among the newest trends in dental composites is the use of graphene oxide (GO) nanoparticles to assure better cohesion of the composite and superior properties. Our research used GO to enhance several hydroxyapatite (HA) nanofiller distribution and cohesion in three experimental composites CC, GS, GZ exposed to coffee and red wine staining environments. The presence of silane A-174 on the filler surface was evidenced by FT-IR spectroscopy. Experimental composites were characterized through color stability after 30 days of staining in red wine and coffee, sorption and solubility in distilled water and artificial saliva. Surface properties were measured by optical profilometry and scanning electron microscopy, respectively, and antibacterial properties wer e assessed against Staphylococcus aureus and Escherichia coli. A colour stability test revealed the best results for GS, followed by GZ, with less stability for CC. Topographical and morphological aspects revealed a synergism between GZ sample nanofiller components that conducted to the lower surface roughness, with less in the GS sample. However, surface roughness variation due to the stain was affected less than colour stability at the macroscopic level. Antibacterial testing revealed good effect against Staphylococcus aureus and a moderate effect against Escherichia coli.

High Performance Epoxy Composites Containing Nanofiller Modified by Plasma Bubbles.

The thermal conductivity of polymer materials is a fundamental parameter in the field of high-voltage electrical insulation. When the operating frequency and power for electrical equipment or electronic devices increase significantly, the internal heat will increase dramatically, and the accumulation of heat will further lead to insulation failure and serious damage of the whole system. The addition of filler with high thermal conductivity into polymer is a common solution. However, the interfacial thermal resistance between filler and bulk materials is the major obstacle to improve thermal conductivity. Herein, in order to reduce the interfacial thermal resistance, nanofillers are modified by plasma technology. The surface modification of nano-Al2O3 is carried out using plasma bubbles with three atmospheres (Ar, Ar+O2, air) as well as coupling agent. The situation of surface grafting before and after the modification is characterized using FTIR, XPS, and SEM. The effect of the mechanism of modification on the thermal conductivity and reaction pathway is investigated. The results showed that the thermal conductivity after plasma modification is increased significantly. Especially, the thermal conductivity is increased by 35% for the sample modified by Ar+O2 atmosphere. This results because more hydroxyl is introduced on the filler surface by the plasma bubbles, which enhance the interface compatibility between filler and epoxy. In addition, surface insulation performance for the modified samples also is enhanced by 14%. This is associated with the change of surface resistance and trap distribution. These results provide potential support for the development of fabrication for high performance epoxy composites.

Surface grafting of Poly (ether ether ketone) on silica particles as novel filler for dental composites: Physico-chemical characterization

This study aimed to describe the fabrication of a novel dental composite by surface modification of silica fillers with polyether ether ketone (PEEK) and assess surface coverage of fillers and the effect of different concentration of modified fillers on degree of conversion, flexural strength, polymerization shrinkage, water sorption and solubility, viscosity and thermal expansion of the formulated composites. In this experimental study, aminosilane derivative of PEEK was synthesized and grafted to the silica filler surface, then evaluated using a fourier transform infrared spectroscopy (FTIR), and thermo-gravimetric analysis (TGA). Silica-PEEK fillers were then mixed with Bis-GMA/TEGDMA resin base in 10, 30, and 50 wt%. The most relevant physico-chemical properties were evaluated and compared with a control composite resin group containing conventional 3-(methacryloxypropyl) trimethoxysilane (γ-MPS) modified fillers. Data were analyzed by ANOVA and Tukey’s HSD test. (α = 5%). The experimental composite with 30% modified fillers showed highest flexural strength and degree of conversion (DC) ( p < 0.05), and comparable polymerization shrinkage and viscosity to the control composites ( p > 0.05). After thermocycling, the composite with 30% modified fillers showed the lowest solubility and water sorption ( p < 0.05). Surface modification of silica fillers with PEEK polymer significantly increases the resistance of the filler–matrix interface to hydrolysis. The above mentioned intervention can improve mechanical properties of the composite and may be considered as a promising protocol to reduce the failure of dental composites.

Jute fibre reinforced unsaturated polyesters laminate preparation using eggshell filler

AbstractThe current work aims to evaluate the properties of unsaturated polyester laminates reinforced with discontinuous randomly oriented chopped jute fibre matrix filled with microsized (57.8 μm) eggshell filler. Laminates with two and three layers of jute fibres were prepared by hand lay‐up process. The mechanical properties like tensile strength, impact strength and flexural strength were enhanced from 20.16 to 25.8 MPa, 1.42 to 3.98 KJ/m2 and 35.54 to 57.84 MPa, respectively, when the eggshell filler (surface area: 72.64 m2/g, pore volume: 0.297 cc/g) content was increased from 0% to 2.5% in the matrix for the three‐layered laminate. The increase in filler content to 5% enhanced the hardness from 21.95 to 90.35 Rockwell L‐scale (two‐layered laminate); however, there was a declination of the other mechanical properties at a high filler content. The microsized filler has significantly decreased the voids and improvised the homogeneity, microstructure, crystallinity and contact angle (from 70.98 [unfilled] to 74.72 [filled]) of the produced filled laminates, as substantiated by scanning electron microscope (SEM), atomic force microscopy (AFM), X‐ray difffraction (XRD) and contact angle measurements. Thus, the fabricated laminates can be efficiently utilised as an eco‐friendly, high‐strength, low‐cost, light material for fabricating automobile dashboards.

Highly thermally conductive polymer-based composites with 3D exfoliated BNNS/functionalized SiC networks prepared by rapid solidification and hot pressing

High thermal conductivity polymer-based packaging materials can achieve effective heat diffusion, which is of great significance for the performance and longevity of electronic devices. Exfoliated boron nitride nanosheets (s-BNNS) containing smaller particle sizes, fewer layers, and more hydroxyl groups were prepared by ball milling and strong ultrasonic treatment in this work. The functionalized SiC (m-SiC) was obtained by ternary blend organic silanol modification, which promoted the compatibility between fillers and fillers, as well as fillers and matrix. By a facile strategy of rapid solidification and hot pressing, s-BNNS were distributed between and on the surface of m-SiC fillers to form m-SiC/s-BNNS/polyamide 6/polyethylene terephthalate (PA6/PET) composite films with 3D thermally conductive networks. The thermal conductivity of m-SiC/s-BNNS/PA6/PET composite reached a superior 6.98 W/(m·K) at a filler loading 85 wt%, which was 124.67% higher than that of SiC/PA6/PET composite without 3D thermal network formation. More interestingly, reverse non-equilibrium molecular dynamics (RNEMD) simulations show that the hybrid SiC/BNNS filler greatly reduces the porosity within the composite compared to only one kind of filler, which in turn improves the composite's thermal conductivity.

Enhanced thermal conductivity and rheological performance of epoxy and liquid crystal epoxy composites with filled Al2O3 compound

The heat dissipation capability of electrical insulation materials has been the bottleneck affecting the development of high power density electrical equipment and electronic devices. In this study, we investigated the effect of filler compounding, filler surface treatment and liquid crystal structure on the microscopic morphology, rheological performance, thermal conductivity and dielectric performance of the epoxy resin (EP) and liquid crystal epoxy resin (LCEP) composites. The results show that the composite with 45 μm and 3 μm Al2O3 compound fillers at a ratio of 3:2 showed a reduction in viscosity for about 1/3-1/30 and an enhancement in thermal conductivity for about 10%–40% compared to the other filler compounds with different filler size and ratio. The filler surface treatment by silane coupling agent diminished the viscosity by up to 90% and simultaneously enhanced the thermal conductivity of the composite by about 10%. The composite with LCEP matrix showed a thermal conductivity up to 2.47 W/(m·K) at 80 wt% filler loading, which is about 0.54 W/(m·K) higher than that of EP based composite. Moreover, the filler surface treatment can improve the electrical breakdown strength and volume resistivity of the composites. The results indicate that filler compound optimization, filler surface treatment and LCEP matrix can significantly improve the thermal conductivity, rheological and dielectric properties of the composites.

Thermal conductive nylon 6 composites with hybrid fillers prepared through reaction during extrusion

Currently, heat dissipation has become one of the key points to the development of novel electronic industry due to the process of miniaturization and integration, while the demand of heat dissipation could not be satisfied by the commonly used polymers. Plenty of methods to promote the thermal conductivity involve complicated steps, which hinder the feasibility of industrial application. In this work, a multi-level local thermal conductive network was designed through the reaction of amino group and epoxy group on the surface of specific fillers in the process of melt mixing to improve the thermal conductivity. The thermal conductivity of the composite prepared with reaction during extrusion was 2.121 W m−1 K−1 at 50 wt% filler content, which is better than similar combination without reaction (1.87 W m−1 K−1). Improved thermal conductivity can be attributed to the synergistic effect of glass fiber (GF) and boron nitride (BN) modified by γ-glycidoxypropyltrimethoxysilane (KH560) and aminopropyl-trimethoxysilane (KH550), respectively. This convenient strategy provides a promising method to further constructing thermal conductive network with enhanced industrial application.

Increase in Properties and Self-Healing Ability of Conductive Butyl Rubber/Epoxidized Natural Rubber Composites by Using Bis(triethoxysilylpropyl)tetrasulfide Coupling Agent.

Flexible self-healing composite was fabricated based on blending the bromobutyl rubber (BIIR) and epoxide natural rubber (ENR) filled with hybrid fillers of carbon nanotubes (CNT) and carbon black (CB). To achieve self-recoverability, modification of BIIR was carried out through butyl imidazole (IM), and the healing capability was then activated by the addition of bis(triethoxysilylpropyl)tetrasulfide (TESPT), which resulted in good dispersion of CNT/CB in BIIR/ENR blends. The silanization of TESPT and CNT/CB hybrid filler surfaces was confirmed by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. Adding CNT/CB and incorporating TESPT into the composites effectively improved the curing and mechanical properties of the blends in terms of estimated crosslink density and tensile modulus. Further, the self-healing propagation rate was enhanced by the thermal conductivity of fillers and the ion-dipole intermolecular forces between the rubber chains, leading to the highest abrasion resistance and electrical conductivity. Using an environmentally friendly process, the recyclability of the self-healing composites was improved by the re-compression of the samples. With this, the constant conductivity relating to the rearrangement of the CNT/CB network is examined related to the usability of the composites at 0 and 60 °C. The conductive composites filled with a TESPT silane coupling agent present an opportunity for vehicle tires and other self-repairing applications.

Effect of Alumina Modified by Silane on the Mechanical, Swelling and Dielectric Properties of Al2O3/EPDM/SBR Blend Composites

Rubber blending has been widely used to improve various properties in finished rubber products. The purpose of this paper is to investigate the effect of filler size, type, concentration, and surface treatment on the mechanical, swelling, dielectric, and morphology properties of ethylene propylene diene rubber (EPDM)/styrene-butadiene rubber (SBR) rubber blend nanocomposites filled with alumina (Al2O3) nanoparticles. Bis-(3-(triethoxysilyl)-propyl)-tetrasulfide (TESPT) was used as a silane coupling agent. Rubber blend nanocomposites containing Al2O3 nanoparticles were compared to carbon black (CB). The results indicate that the nanocomposites prepared, in particular with the TESPT, had better properties than the composites without the TESPT. Mechanical properties of the CB-filled EPDM/SBR rubber blend were noticeably improved, indicating CB's inherent reinforcing potential. We found that rubber nanocomposites' crosslink density and filler–rubber interaction increase, and the swelling coefficient decreases with increasing filler content. The dielectric properties of the nanocomposites showed a significant enhancement with fillers. SEM images showed that the CB sample had a higher distribution than Al2O3 due to good interaction and dispersion. This study's experimental data will help design and manufacture outdoor insulators.

Influence of Alkali Treatment of Jatropha Curcas L. Filler on the Service Life of Hybrid Adhesive Bonds under Low Cycle Loading

The aim of this research was to evaluate the effect of untreated and 5% aqueous NaOH solution-treated filler of the plant Jatropha Curcas L. on the mechanical properties of adhesive bonds, especially in terms of their service life at different amplitudes of cyclic loading. As a result of the presence of phorbol ester, which is toxic, Jatropha oilseed cake cannot be used as livestock feed. The secondary aim was to find other possibilities for the utilization of natural waste materials. Another use is as a filler in polymer composites, that is, in composite adhesive layers. The cyclic loading of the adhesive bonds was carried out for 1000 cycles in two amplitudes, that is, 5-30% of the maximum force and 5-50% of the maximum force, which was obtained by the static tensile testing of the adhesive bonds with unmodified filler. The static tensile test showed an increase in the shear strength of the adhesive bonds with alkali-treated filler compared to the untreated filler by 3-41%. The cyclic test results did not show a statistically significant effect of the alkaline treatment of the filler surface on the service life of the adhesive bonds. Positive changes in the strain value between adhesive bonds with treated and untreated filler were demonstrated at cyclic stress amplitudes of 5-50%. SEM analysis showed the presence of interlayer defects in the layers of the tested materials, which are related to the oil-based filler used.

Understanding the balance between additives' miscibility and plasticisation effect in polymer composites: a computational study.

Plasticisers are small organic molecules routinely added to polymer composites that modify the processability of the compounds by adsorbing on the filler's surface or dispersing into the polymer matrix. Here using a simple yet chemically specific coarse-grained model, we demonstrate that the filler surface coverage and the degree of dispersion into the polymer matrix can be tuned without modifying the chemistry of the plasticisers but only by varying their conformational flexibility. We show that when the adsorption mechanism and clustering into the bulk are entropically driven as in this work, this is a general phenomenon independent on the polymer chemistry and its molecular weight. Our findings suggest a simple practical design rule that requires only minor modifications of the plasticisers' chemistry to achieve maximum adsorption onto the filler surface or dispersion into the polymer matrix.